> ## Documentation Index > Fetch the complete documentation index at: https://docs.metriport.com/llms.txt > Use this file to discover all available pages before exploring further. # ElementDefinition > Base StructureDefinition for ElementDefinition Type: Captures constraints on each element within the resource, profile, or extension. ## Properties | Name | Required | Type | Description | | ------------------- | -------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------- | | id | No | string | Unique id for inter-element referencing | | extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations | | modifierExtension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Extensions that cannot be ignored even if unrecognized | | path | Yes | string | Path of the element in the hierarchy of elements | | representation | No | code\[] | xmlAttr / xmlText / typeAttr / cdaText / xhtml | | sliceName | No | string | Name for this particular element (in a set of slices) | | sliceIsConstraining | No | boolean | If this slice definition constrains an inherited slice definition (or not) | | label | No | string | Name for element to display with or prompt for element | | code | No | [Coding](/medical-api/fhir/data-types/coding)\[] | Corresponding codes in terminologies | | slicing | No | Element | This element is sliced - slices follow | | - id | No | string | Unique id for inter-element referencing | | - extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations | | - discriminator | No | Element\[] | Element values that are used to distinguish the slices | | - id | No | string | Unique id for inter-element referencing | | - extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations | | - type | Yes | code | value / exists / pattern / type / profile | | - path | Yes | string | Path to element value | | - description | No | string | Text description of how slicing works (or not) | | - ordered | No | boolean | If elements must be in same order as slices | | - rules | Yes | code | closed / open / openAtEnd | | short | No | string | Concise definition for space-constrained presentation | | definition | No | markdown | Full formal definition as narrative text | | comment | No | markdown | Comments about the use of this element | | requirements | No | markdown | Why this resource has been created | | alias | No | string\[] | Other names | | min | No | unsignedInt | Minimum Cardinality | | max | No | string | Maximum Cardinality (a number or \*) | | base | No | Element | Base definition information for tools | | - id | No | string | Unique id for inter-element referencing | | - extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations | | - path | Yes | string | Path that identifies the base element | | - min | Yes | unsignedInt | Min cardinality of the base element | | - max | Yes | string | Max cardinality of the base element | | contentReference | No | uri | Reference to definition of content for the element | | type | No | Element\[] | Data type and Profile for this element | | - id | No | string | Unique id for inter-element referencing | | - extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations | | - code | Yes | uri | Data type or Resource (reference to definition) | | - profile | No | canonical\[] | Profiles (StructureDefinition or IG) - one must apply | | - targetProfile | No | canonical\[] | Profile (StructureDefinition or IG) on the Reference/canonical target - one must apply | | - aggregation | No | code\[] | contained / referenced / bundled - how aggregated | | - versioning | No | code | either / independent / specific | | defaultValue\[x] | No | base64Binary, boolean, canonical, code, date, dateTime, decimal, id, instant, integer, markdown, oid, positiveInt, string, time, unsignedInt, uri, url, uuid, [Address](/medical-api/fhir/data-types/address), [Age](/medical-api/fhir/data-types/age), [Annotation](/medical-api/fhir/data-types/annotation), [Attachment](/medical-api/fhir/data-types/attachment), [CodeableConcept](/medical-api/fhir/data-types/codeableconcept), [Coding](/medical-api/fhir/data-types/coding), [ContactPoint](/medical-api/fhir/data-types/contactpoint), [Count](/medical-api/fhir/data-types/count), [Distance](/medical-api/fhir/data-types/distance), [Duration](/medical-api/fhir/data-types/duration), [HumanName](/medical-api/fhir/data-types/humanname), [Identifier](/medical-api/fhir/data-types/identifier), [Money](/medical-api/fhir/data-types/money), [Period](/medical-api/fhir/data-types/period), [Quantity](/medical-api/fhir/data-types/quantity), [Range](/medical-api/fhir/data-types/range), [Ratio](/medical-api/fhir/data-types/ratio), Reference\<>, [SampledData](/medical-api/fhir/data-types/sampleddata), [Signature](/medical-api/fhir/data-types/signature), [Timing](/medical-api/fhir/data-types/timing), [ContactDetail](/medical-api/fhir/data-types/contactdetail), [Contributor](/medical-api/fhir/data-types/contributor), [DataRequirement](/medical-api/fhir/data-types/datarequirement), [Expression](/medical-api/fhir/data-types/expression), [ParameterDefinition](/medical-api/fhir/data-types/parameterdefinition), [RelatedArtifact](/medical-api/fhir/data-types/relatedartifact), [TriggerDefinition](/medical-api/fhir/data-types/triggerdefinition), [UsageContext](/medical-api/fhir/data-types/usagecontext), [Dosage](/medical-api/fhir/data-types/dosage), [Meta](/medical-api/fhir/data-types/meta) | Specified value if missing from instance | | meaningWhenMissing | No | markdown | Implicit meaning when this element is missing | | orderMeaning | No | string | What the order of the elements means | | fixed\[x] | No | base64Binary, boolean, canonical, code, date, dateTime, decimal, id, instant, integer, markdown, oid, positiveInt, string, time, unsignedInt, uri, url, uuid, [Address](/medical-api/fhir/data-types/address), [Age](/medical-api/fhir/data-types/age), [Annotation](/medical-api/fhir/data-types/annotation), [Attachment](/medical-api/fhir/data-types/attachment), [CodeableConcept](/medical-api/fhir/data-types/codeableconcept), [Coding](/medical-api/fhir/data-types/coding), [ContactPoint](/medical-api/fhir/data-types/contactpoint), [Count](/medical-api/fhir/data-types/count), [Distance](/medical-api/fhir/data-types/distance), [Duration](/medical-api/fhir/data-types/duration), [HumanName](/medical-api/fhir/data-types/humanname), [Identifier](/medical-api/fhir/data-types/identifier), [Money](/medical-api/fhir/data-types/money), [Period](/medical-api/fhir/data-types/period), [Quantity](/medical-api/fhir/data-types/quantity), [Range](/medical-api/fhir/data-types/range), [Ratio](/medical-api/fhir/data-types/ratio), Reference\<>, [SampledData](/medical-api/fhir/data-types/sampleddata), [Signature](/medical-api/fhir/data-types/signature), [Timing](/medical-api/fhir/data-types/timing), [ContactDetail](/medical-api/fhir/data-types/contactdetail), [Contributor](/medical-api/fhir/data-types/contributor), [DataRequirement](/medical-api/fhir/data-types/datarequirement), [Expression](/medical-api/fhir/data-types/expression), [ParameterDefinition](/medical-api/fhir/data-types/parameterdefinition), [RelatedArtifact](/medical-api/fhir/data-types/relatedartifact), [TriggerDefinition](/medical-api/fhir/data-types/triggerdefinition), [UsageContext](/medical-api/fhir/data-types/usagecontext), [Dosage](/medical-api/fhir/data-types/dosage), [Meta](/medical-api/fhir/data-types/meta) | Value must be exactly this | | pattern\[x] | No | base64Binary, boolean, canonical, code, date, dateTime, decimal, id, instant, integer, markdown, oid, positiveInt, string, time, unsignedInt, uri, url, uuid, [Address](/medical-api/fhir/data-types/address), [Age](/medical-api/fhir/data-types/age), [Annotation](/medical-api/fhir/data-types/annotation), [Attachment](/medical-api/fhir/data-types/attachment), [CodeableConcept](/medical-api/fhir/data-types/codeableconcept), [Coding](/medical-api/fhir/data-types/coding), [ContactPoint](/medical-api/fhir/data-types/contactpoint), [Count](/medical-api/fhir/data-types/count), [Distance](/medical-api/fhir/data-types/distance), [Duration](/medical-api/fhir/data-types/duration), [HumanName](/medical-api/fhir/data-types/humanname), [Identifier](/medical-api/fhir/data-types/identifier), [Money](/medical-api/fhir/data-types/money), [Period](/medical-api/fhir/data-types/period), [Quantity](/medical-api/fhir/data-types/quantity), [Range](/medical-api/fhir/data-types/range), [Ratio](/medical-api/fhir/data-types/ratio), Reference\<>, [SampledData](/medical-api/fhir/data-types/sampleddata), [Signature](/medical-api/fhir/data-types/signature), [Timing](/medical-api/fhir/data-types/timing), [ContactDetail](/medical-api/fhir/data-types/contactdetail), [Contributor](/medical-api/fhir/data-types/contributor), [DataRequirement](/medical-api/fhir/data-types/datarequirement), [Expression](/medical-api/fhir/data-types/expression), [ParameterDefinition](/medical-api/fhir/data-types/parameterdefinition), [RelatedArtifact](/medical-api/fhir/data-types/relatedartifact), [TriggerDefinition](/medical-api/fhir/data-types/triggerdefinition), [UsageContext](/medical-api/fhir/data-types/usagecontext), [Dosage](/medical-api/fhir/data-types/dosage), [Meta](/medical-api/fhir/data-types/meta) | Value must have at least these property values | | example | No | Element\[] | Example value (as defined for type) | | - id | No | string | Unique id for inter-element referencing | | - extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations | | - label | Yes | string | Describes the purpose of this example | | - value\[x] | Yes | base64Binary, boolean, canonical, code, date, dateTime, decimal, id, instant, integer, markdown, oid, positiveInt, string, time, unsignedInt, uri, url, uuid, [Address](/medical-api/fhir/data-types/address), [Age](/medical-api/fhir/data-types/age), [Annotation](/medical-api/fhir/data-types/annotation), [Attachment](/medical-api/fhir/data-types/attachment), [CodeableConcept](/medical-api/fhir/data-types/codeableconcept), [Coding](/medical-api/fhir/data-types/coding), [ContactPoint](/medical-api/fhir/data-types/contactpoint), [Count](/medical-api/fhir/data-types/count), [Distance](/medical-api/fhir/data-types/distance), [Duration](/medical-api/fhir/data-types/duration), [HumanName](/medical-api/fhir/data-types/humanname), [Identifier](/medical-api/fhir/data-types/identifier), [Money](/medical-api/fhir/data-types/money), [Period](/medical-api/fhir/data-types/period), [Quantity](/medical-api/fhir/data-types/quantity), [Range](/medical-api/fhir/data-types/range), [Ratio](/medical-api/fhir/data-types/ratio), Reference\<>, [SampledData](/medical-api/fhir/data-types/sampleddata), [Signature](/medical-api/fhir/data-types/signature), [Timing](/medical-api/fhir/data-types/timing), [ContactDetail](/medical-api/fhir/data-types/contactdetail), [Contributor](/medical-api/fhir/data-types/contributor), [DataRequirement](/medical-api/fhir/data-types/datarequirement), [Expression](/medical-api/fhir/data-types/expression), [ParameterDefinition](/medical-api/fhir/data-types/parameterdefinition), [RelatedArtifact](/medical-api/fhir/data-types/relatedartifact), [TriggerDefinition](/medical-api/fhir/data-types/triggerdefinition), [UsageContext](/medical-api/fhir/data-types/usagecontext), [Dosage](/medical-api/fhir/data-types/dosage), [Meta](/medical-api/fhir/data-types/meta) | Value of Example (one of allowed types) | | minValue\[x] | No | date, dateTime, instant, time, decimal, integer, positiveInt, unsignedInt, [Quantity](/medical-api/fhir/data-types/quantity) | Minimum Allowed Value (for some types) | | maxValue\[x] | No | date, dateTime, instant, time, decimal, integer, positiveInt, unsignedInt, [Quantity](/medical-api/fhir/data-types/quantity) | Maximum Allowed Value (for some types) | | maxLength | No | integer | Max length for strings | | condition | No | id\[] | Reference to invariant about presence | | constraint | No | Element\[] | Condition that must evaluate to true | | - id | No | string | Unique id for inter-element referencing | | - extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations | | - key | Yes | id | Target of 'condition' reference above | | - requirements | No | string | Why this constraint is necessary or appropriate | | - severity | Yes | code | error / warning | | - human | Yes | string | Human description of constraint | | - expression | No | string | FHIRPath expression of constraint | | - xpath | No | string | XPath expression of constraint | | - source | No | canonical | Reference to original source of constraint | | mustSupport | No | boolean | If the element must be supported | | isModifier | No | boolean | If this modifies the meaning of other elements | | isModifierReason | No | string | Reason that this element is marked as a modifier | | isSummary | No | boolean | Include when \_summary = true? | | binding | No | Element | ValueSet details if this is coded | | - id | No | string | Unique id for inter-element referencing | | - extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations | | - strength | Yes | code | required / extensible / preferred / example | | - description | No | string | Human explanation of the value set | | - valueSet | No | canonical | Source of value set | | mapping | No | Element\[] | Map element to another set of definitions | | - id | No | string | Unique id for inter-element referencing | | - extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations | | - identity | Yes | id | Reference to mapping declaration | | - language | No | code | Computable language of mapping | | - map | Yes | string | Details of the mapping | | - comment | No | string | Comments about the mapping or its use |